JPH1078332A - Encoder original position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an encoder original position detector which can detect an original position with high accuracy. SOLUTION: In an encoder original position detector 1, a light source part 2 irradiates a light beam 5 having an elliptic shape to a detection part 4 by using a reference position part 3 as part of a main scale 6. The detection part 4 comprises two PDs(photodiodes) 8A and 8B disposed in a direction perpendicular to a direction (X direction) of moving the main scale 6. The light source part 2 and the detection part 4 are disposed at a position where the light beam 5 is irradiated equally to the PD 8A and 8B when there is no main scale 6 and the light source 2 is disposed in a state wherein a longitudinal axis direction of a rectangle shaped slit 7 formed in the reference position part 3 is inclined by a predetermined angle to intersect a longitudinal axis direction of a cross section 5A of the light beam 5 from the light source part 2. Consequently, the movement of the main scale 6 can change the shape of the light beam 5 incident on the PD 8A and 8B passing through the slit 7 to accurately detect a reference position where the light beam 5 incident on the PD 8A and 8B are equal in quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an origin position detecting device for an encoder, and more particularly to an origin position detecting device for an encoder capable of detecting the origin position of an encoder with high accuracy.

[0002]

2. Description of the Related Art Recently, encoders have played an important role in micromachining.
Further, in order to detect the displacement of the movable body with high accuracy, it is necessary to detect the origin position (reference position) with high accuracy.

Therefore, an encoder for detecting the origin of the encoder has been proposed (Japanese Patent Laid-Open No. Sho 62-62).
2002223).

This encoder makes a light beam incident on a diffraction grating connected to a moving object to be measured, and measures a moving state of the moving object by using a diffracted light of a specific order out of the diffracted light from the diffraction grating. A light beam is made incident on a reference position detection unit comprising a slit provided in a part of the moving object to be detected, and a transmitted light beam or a reflected light beam from the reference position detection unit is guided to light receiving means having two light receiving surfaces. In addition, a reference signal relating to the moving object to be detected is obtained by using an output signal from the light receiving unit.

Therefore, according to this encoder, for example, in the case of a rotary encoder having a disc, 1
One reference signal can be obtained per rotation.

[0006]

However, in such a conventional encoder origin position detecting device,
Since the light reflected or transmitted by the slit is detected, in order to increase the resolution to the submicron order,
Although it is necessary to narrow the slit width, it is difficult to form a slit of several microns or less, and there is a problem that irradiation with a laser beam causes diffraction and deteriorates accuracy.

Therefore, the invention according to claim 1 is to provide a light beam having a cross section perpendicular to the emission direction having a predetermined elongated cross section.
The light is emitted from the light source unit to the main scale, and the light beam from the light source unit is cut out by a predetermined elongated light shaping unit formed on the main scale, and two or more light receiving elements are moved in the direction of mutual movement with the main scale means. The light receiving means arranged at right angles to the light receiving means is reflected or transmitted, and the light receiving means receives the light and performs photoelectric conversion. The major axis of the cross-sectional shape of the light beam emitted from the light source unit and the major axis of the light shaping unit are aligned. By being inclined at a predetermined angle, even when a wide slit or a reflection member is formed as a light forming portion of the main scale, by two or more light receiving elements of the light receiving means,
It is an object of the present invention to provide an encoder origin position detecting device capable of detecting an origin position with high resolution by detecting a light beam deformed by mutual movement with a main scale.

According to a second aspect of the present invention, the light emitted from the light-emitting element is condensed by a cylindrical lens to emit a light beam whose cross section perpendicular to the light emitting direction has a predetermined elongated cross-sectional shape. It is another object of the present invention to provide an encoder origin position detecting device capable of efficiently emitting a linear light beam and detecting the origin position with high resolution.

According to a third aspect of the present invention, the light source unit is provided with a mask means having two openings for dividing the light into two light beams having different phases.
Origin position detection of an encoder that can form two linear beams, reduces the noise by using two light beams, and can detect the origin position more simply, inexpensively, and with higher resolution. It is intended to provide a device.

According to a fourth aspect of the present invention, the light source unit emits a light beam whose major axis in cross section is substantially perpendicular to the direction of relative movement with respect to the main scale means. Are formed at a predetermined angle with respect to the major axis direction of the cross-sectional shape of the light beam from the light source unit, so that the long-axis direction of the cross-sectional shape of the light beam emitted from the light source unit moves in the relative movement direction with the main scale means. Just arrange it approximately at right angles to
The optical molding unit can be tilted at a predetermined angle to the long axis direction without fine rotation adjustment of the lens or light source, etc., and the origin position can be detected easily and inexpensively with high resolution. It is an object of the present invention to provide an encoder origin position detecting device which can perform the operation.

According to a fifth aspect of the present invention, the light source unit is provided with mask means having an opening having a rectangular or elliptical cross section perpendicular to the emission direction of the transmitted light beam. Thereby, a light beam whose cross section perpendicular to the emission direction has a predetermined elongated cross-sectional shape can be produced at low cost, and
It is an object of the present invention to provide an encoder origin position detecting device capable of efficiently emitting light and detecting the origin position with high resolution.

According to a sixth aspect of the present invention, the light source unit includes a laser diode for emitting light beams having different radiation angles in a cross section of the emitted light beam, and a lens for condensing or collimating the emitted light from the laser diode. With a small number of components, a light beam having a thin and long cross section perpendicular to the emission direction can be easily formed and emitted, and the origin position can be detected with high resolution even in a wide slit. It is an object of the present invention to provide an inexpensive encoder origin position detecting device that can perform the operation.

According to a seventh aspect of the present invention, a light emitting diode having a light emitting surface elongated in one direction is used as a light source.
It is an object of the present invention to provide an inexpensive origin position detecting device for an encoder that can easily and inexpensively emit an elongated light flux and detect the origin position with high resolution even in a wide slit.

[0014]

According to a first aspect of the present invention, there is provided an encoder origin position detecting device for detecting an origin position of an encoder which outputs an electric signal corresponding to a displacement of a movable body. A light source unit for irradiating a light beam having a cross section perpendicular to the emission direction thereof having a predetermined elongated cross-sectional shape, and a light forming unit having a predetermined elongate shape for cutting out the light beam from the light source and reflecting or transmitting the light beam. Main scale means, and light receiving means for receiving the light flux from the light shaping section and performing photoelectric conversion, wherein the light receiving means is disposed in a direction perpendicular to the direction of mutual movement with the main scale means. At least two or more light receiving elements, and the major axis of the cross-sectional shape of the emitted light beam of the light source unit and the major axis of the light shaping unit are inclined at a predetermined angle. More, it has achieved the above object.

According to the above construction, a light beam having a cross section perpendicular to the emission direction having a predetermined elongated cross-sectional shape is emitted from the light source section to the main scale, and a predetermined elongated light shaping section formed on the main scale is formed. The light beam from the light source section is cut off, and two or more light receiving elements are reflected or transmitted by a light receiving means arranged at a right angle to the direction of mutual movement with the main scale means, and the light is received by the light receiving means. Since the photoelectric conversion is performed and the long axis of the cross-sectional shape of the light beam emitted from the light source unit and the long axis direction of the light forming unit are inclined at a predetermined angle, a wide slit or a reflecting member is used as the light forming unit of the main scale. Even if formed,
By using two or more light receiving elements of the light receiving means, a light beam deformed by mutual movement with the main scale can be detected, and the origin position can be detected with high resolution.

In this case, for example, as described in claim 2, the light source unit includes a light emitting element for emitting light and a cylindrical lens for condensing the light emitted from the light emitting element. Is also good.

According to the above configuration, since the light emitted from the light emitting element is condensed by the cylindrical lens, a light beam having a predetermined elongated cross section perpendicular to the emission direction can be emitted, and the cost can be reduced. In addition, a linear light beam can be efficiently emitted. As a result, it is possible to reduce the cost of the encoder origin position detecting device capable of detecting the origin position with high resolution.

Further, for example, as described in claim 3, the light source unit may include a mask means formed with two openings for dividing light into two light beams having different phases. .

According to the above configuration, the light source unit is provided with the mask means having the two apertures for dividing the light into two light beams having different phases. Can be formed, the number of light beams can be reduced to two, noise can be reduced, and the origin position can be detected at low cost and with higher resolution.

Further, for example, as described in claim 4, the light source unit emits the light beam whose major axis in cross section is substantially perpendicular to the direction of relative movement with respect to the main scale means. The light shaping portion may be formed such that its major axis is inclined at a predetermined angle with respect to the major axis direction of the cross-sectional shape of the light beam from the light source.

According to the above arrangement, the light source emits a light beam whose major axis in cross section is substantially perpendicular to the direction of relative movement with respect to the main scale means. Is formed at a predetermined angle with respect to the major axis direction of the cross-sectional shape of the light beam from the unit, so that the long-axis direction of the cross-sectional shape of the light beam emitted from the light source unit is in the direction of relative movement with the main scale means. Just by arranging it at a substantially right angle to it, it is possible to make it inclined at a predetermined angle with respect to the long axis direction of the light forming part without performing fine rotation adjustment of the lens, light source, etc., and it is easy to assemble, The origin position can be detected at low cost and with high resolution.

Further, for example, the light source unit may include a mask means having an opening having a rectangular or elliptical cross section perpendicular to the emission direction of the transmitted light beam. , May be provided.

According to the above arrangement, the light source unit is provided with the mask means having the opening having a rectangular or elliptical cross section perpendicular to the emission direction of the transmitted light beam. It is possible to inexpensively and efficiently emit a light beam whose cross section perpendicular to the emission direction has a predetermined elongated cross-sectional shape, and it is possible to detect the origin position at low cost and with high resolution.

Further, for example, the light source unit includes a laser diode that emits a light beam having a different radiation angle within a cross section of the emitted light beam, and condenses light emitted from the laser diode. Alternatively, a lens for collimating may be provided.

According to the above configuration, the light source unit includes the laser diode that emits light beams having different emission angles within the cross section of the emitted light beam, and the lens that collects or parallelizes the light emitted from the laser diode. Since it is provided with a small number of parts, it is possible to easily form and emit a light beam with a cross section perpendicular to the emission direction with a small number of parts, and it is inexpensive and has high resolution even in a wide slit. , The origin position can be detected.

Further, for example, the light source section may include a light emitting diode having a light emitting surface which is elongated in one direction as a light source.

According to the above configuration, since the light source is a light emitting diode having a light emitting surface which is elongated in one direction, an elongated light beam can be emitted easily and inexpensively, and even a wide slit can be inexpensively manufactured. In addition, the origin position can be detected with high resolution.

[0028]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

FIGS. 1 to 3 show a first embodiment of an origin position detecting device for an encoder according to the present invention. This embodiment corresponds to claim 1 of the present invention.

FIG. 1 is a perspective view of an encoder origin position detecting device 1 to which the first embodiment of the encoder origin position detecting device of the present invention is applied.

Referring to FIG. 1, an origin position detecting device 1 for an encoder includes a light source unit 2, a reference position unit 3, a detecting unit 4, and the like.

The light source section 2 includes a light source formed of a light emitting element such as a semiconductor laser, a lens for condensing light emitted from the light source, and the like. Is irradiated to the detection unit 4 via the reference position unit 3.

The reference position 3 is provided on a part of the main scale (main scale means) 6 of the encoder. The reference position 3 has a rectangular slit (light shaping portion) 7 formed therein.

The detecting section 4 is disposed on the opposite side of the light source section 3 with the reference position section 3 of the main scale 6 interposed therebetween. As shown in FIG. 2, the PD (Photo Diode) 8A, 8 is divided into two parts.
B, the light source unit 3 incident through the reference position unit 3
Photoelectrically converts the light from

When the main scale 6 is not provided, the light source unit 2 and the detection unit 4
8A and 8B are disposed at positions where the same amount of light beam 5 irradiates both regions.
And a long axis direction of the light beam 5 emitted from the light source unit 2 (a light beam cross section) 5A is disposed so as to intersect with a predetermined angle of inclination.

The light source section 2 and the detection section 4 are fixed to the head section of the encoder, and the slit 5 is formed by the movement of the head section or the main scale 6 (in this embodiment, the movement in the X direction in FIG. 1). The light crosses the light beam 5 of the light emitted from the light source unit 2 toward the detection unit 4.

Next, the operation of this embodiment will be described. As described above, the origin position detecting device 1 of the encoder has the light source unit 2 and the detecting unit 4 fixed to the head unit (not shown) of the encoder, and the reference position unit 3 is the main scale 6 of the encoder.
Is provided in a part of.

In this state, when light is emitted from the light source unit 2 to the detection unit 4 and the head unit or the main scale moves, the slit 7 of the reference position unit 3 crosses the light beam 5.

If the main scale 6 moves, the major axis of the cross section 5A of the light beam 5 and the major axis of the slit 7 intersect with a predetermined angle of inclination. Accordingly, the light beam 5 that has passed through the slit 7 changes from the state of FIG. 2A to the state of FIG. 2B to the state of FIG.
The shape of the light beam 5 incident on the light source changes at this time. At this time, as shown in FIG. 3, the PD 8A and the PD 8B change the output signal SA and the output signal SB in accordance with the positions (a) to (c) in FIG. Output.

Here, assuming that a position where the light amount of the light beam 5 incident on the PD 8A and the PD 8B of the detecting unit 4 becomes the same is a reference position (origin position), the output signal S of the PD 8A after photoelectric conversion is obtained.
The reference position can be detected with high precision by comparing the output signal A and the photoelectrically converted output signal of the PD 8B with the SB.

As described above, according to the present embodiment, the light beam (light beam) 5 whose cross section 5A perpendicular to the emission direction has a predetermined elongated cross section is emitted from the light source unit 2 to the main scale 6, and The light beam 5 from the light source unit 2 is cut out by a slit 7 which is a rectangular light shaping unit formed on the scale 6, and two or more light receiving elements PD8A, 8B
Is transmitted through a light receiving unit 4 which is a light receiving unit disposed at a right angle to the direction of movement with respect to the main scale 6, received by the light receiving unit 4, photoelectrically converted, and a light beam emitted from the light source unit 2. 5, the long axis of the cross section 5A and the slit 7
Since the major axis direction is inclined at a predetermined angle, even when a wide slit or the like is formed as the slit 7 of the main scale 6, the two PDs 8A
With 8B, the origin position can be detected with high resolution.

FIG. 4 is a diagram showing a second embodiment of the reference position detecting device for the encoder according to the present invention, and this embodiment corresponds to claim 2. In this embodiment, the light source unit is constituted by a light source and a cylindrical lens, and the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be described. Omitted.

Referring to FIG. 4, an encoder origin position detecting device 10 includes a light source 11, a reference position 3, and a detecting unit 4.

The light source section 11 includes a light emitting element 12 such as a semiconductor laser as a light source, and a cylindrical lens 13 for condensing light emitted from the light emitting element 12, and transmits the light beam 5 through the reference position section 3. Irradiate the detection unit 4. The cylindrical lens 13 is disposed in a state of being rotated such that the major axis direction of the slit 7 and the major axis direction of a cross section (ray cross section) 14A of the light ray 14 intersect with a predetermined angle of inclination. .

The reference position unit 3 and the detection unit 4 are configured in the same manner as in the first embodiment.

Therefore, the origin position detecting device 10 of the encoder according to the present embodiment collects the light emitted from the light emitting element 12 of the light source unit 11 by the cylindrical lens 13 and passes through the slit 7 of the reference position unit 3. To the detector 4.

At this time, the ratio of the major axis to the minor axis of the cross section 14A of the light emitted from the light emitting element 12 in the direction perpendicular to the emission direction of the light beam 14 is adjusted by the cylindrical lens 13 according to the first embodiment. The ratio of the major axis to the minor axis of the cross section 5 </ b> A of the light beam 5 is larger than the ratio of the major axis to the minor axis.
It is possible to increase the difference in the amount of light emitted to 8A and 8B. As a result, the noise component for the signal component is reduced, and the detection accuracy can be improved.

FIG. 5 is a view showing a third embodiment of the reference position detecting device for the encoder according to the present invention, and this embodiment corresponds to claim 3. In this embodiment, a mask is provided in the light source unit, and the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. .

In FIG. 5, the origin position detecting device 20 of the encoder includes a light source unit 21, a reference position unit 3, and a detecting unit 4.
(Not shown).

The light source section 21 includes a light emitting element 22 such as a semiconductor laser as a light source, a lens 23 for condensing light emitted from the light emitting element 22, and a mask 24. Irradiate the detection unit 4 via the position unit 3.

The mask 24 has two openings 25A, 2A
5B is formed, and the light condensed by the lens 23 is applied to the openings 25A and 25B. The openings 25A and 25B of the mask 24 are formed at positions that fall within the cross section 26A of the light beam 26 of the light condensed by the lens 23, and convert the light from the lens 23 into two light beams (light flux) 27A and 27B.
And irradiate the slit 7 of the reference position 3.

The openings 25A and 25B are
The light that has passed through 25B is applied to PDs 8A and 8B, respectively, and is formed at a position where the phases are different.

The reference position unit 3 and the detection unit 4 are configured in the same manner as in the first and second embodiments.

Therefore, the origin position detecting device 20 of the encoder according to the present embodiment condenses the light emitted from the light emitting element 22 of the light source section 21 by the lens 23 and
Through the openings 25A and 25B of the mask 24.
A, 27B, and irradiate the reference position part 3;
Irradiation is performed on the detection unit 4 through the slit 7 of the reference position unit 3.

At this time, the openings 25A, 2A
The light beams 27A and 27B of the light having passed through 5B
Irradiates the PDs 8A and 8B sequentially with the movement of.

As a result, PD8A and PD8B
Assuming that a position at which the amount of light rays incident on the PD 8A becomes the same is a reference position, the reference position can be detected by comparing the photoelectrically converted output signal of the PD 8A with the photoelectrically converted output signal of the PD 8B.

Since the light rays 26 of the light emitted from the light source unit 21 are separated by the openings 25A and 25B of the mask 24, noise can be reduced and the resolution can be improved.

FIG. 6 is a diagram showing a fourth embodiment of the reference position detecting device for an encoder according to the present invention, and this embodiment corresponds to claim 4. In the present embodiment, the slit at the reference position is inclined with respect to the light beam of the light source unit, and the same components as those in the first embodiment are denoted by the same reference numerals. Therefore, a detailed description thereof will be omitted.

In FIG. 6, an encoder origin position detecting device 30 includes a light source unit 31, a reference position unit 32, and a detecting unit 4.
Etc. are provided.

The light source unit 31 includes, for example, a light emitting element such as a semiconductor laser as a light source, and a lens for condensing light emitted from the light emitting element, and irradiates the detection unit 4 with a light beam via the reference position unit 32. I do. The light source section 31 is formed at right angles to the length direction of the main scale 6 where the reference position section 32 is provided.

The reference position 32 is provided on a part of the main scale 6 of the encoder, as in the first embodiment, and a slit 33 is formed in the reference position 32. The slit 33 has a long axis direction 33T whose light source section 3
1 is disposed so as to rotate so as to intersect at a predetermined angle θ with respect to a long-axis direction 34T of a cross section (ray cross section) 34 of a light beam emitted from 1.

The detecting section 4 is the same as that of the first embodiment, and is provided on the opposite side of the light source section 31 with the reference position section 32 interposed therebetween, and includes two divided PDs 8A and 8B. Thus, the light from the light source unit 31 incident via the reference position unit 32 is photoelectrically converted.

The light source unit 31 and the detection unit 4
When there is no main scale 6, the two P
It is disposed at a position where the same amount of light is irradiated to both areas D8A and 8B.

Therefore, in the encoder origin position detecting device 30 of the present embodiment, when light is emitted from the light source unit 31 to the detecting unit 4 and the head unit or the main scale 6 moves, the slit of the reference position unit 32 33 crosses the ray. Assuming that the main scale 6 has moved, since the major axis direction 33T of the slit 33 intersects with the major axis direction 34T of the cross section 34 of the light ray at an inclination of a predetermined angle θ, the main scale 6 moves. As a result, the shapes of the light rays that pass through the slit 33 and enter the PDs 8A and 8B of the detection unit 4 change, and the PDs 8A and PD of the detection unit 4 change.
The output signal of 8B changes as shown in FIG.

Therefore, PD8A and PD8A
Assuming that a position at which the light amount of the light beam incident on B becomes the same is a reference position, the reference position is appropriately and accurately determined by comparing the photoelectrically converted output signal of PD8A and the photoelectrically converted output signal of PD8B. Can be detected.

In the present embodiment, since the slit 33 of the reference position 32 is formed to be inclined,
If the light source, the lens, and the like of the light source unit 31 are set at right angles to the main scale 6, there is no need to adjust the rotation, and the assemblability of the origin position detecting device 30 can be improved. It can be inexpensive.

FIG. 7 is a diagram showing a fifth embodiment of the reference position detecting device for an encoder according to the present invention. This embodiment corresponds to claim 5. In the present embodiment, a mask for elongating the cross-sectional shape of a light beam is provided in the light source unit. Components similar to those in the first embodiment are denoted by the same reference numerals. Therefore, a detailed description thereof will be omitted.

In FIG. 7, an encoder origin position detecting device 40 includes a light source 41, a reference position 3, and a detector 4.
(Not shown).

The light source section 41 includes a light emitting element 42 such as a semiconductor laser as a light source, a lens 43 for condensing light emitted from the light emitting element 42, and a mask 44.
Is irradiated on the detection unit 4 via the mask 44 and the reference position unit 3.

The mask 44 has an elongated rectangular opening 4.
6 is formed, and the light condensed by the lens 43 is applied to the opening 46. The opening 46 of the mask 44
It is formed at a position within the cross section 45A of the light beam 45 condensed by the lens 43. The light from the lens 43 is formed into an elongated rectangular light beam 47, and the slit 7 of the reference position portion 3 is formed.
Irradiated.

The slit 7 at the reference position 3 is formed at right angles to the length direction of the main scale 6, and the opening 46 of the mask 44 is inclined at a predetermined angle with respect to the slit 7. While being formed in the state, the light that has passed through the opening 46 is
B are formed at positions where the same amount of light is applied to B.

The reference position unit 3 and the detection unit 4 are configured in the same manner as in the first embodiment.

Therefore, the origin position detecting device 40 of the encoder according to the present embodiment condenses the light emitted from the light emitting element 42 of the light
Is formed into an elongated rectangular light beam 47 by the opening 46 of the mask 44, irradiates the reference position 3, and further irradiates the detection unit 4 through the slit 7 of the reference position 3.

At this time, the light ray 47 of the light that has passed through the opening 46 of the mask 44 sequentially becomes P
D8A and 8B are irradiated.

As a result, PD8A and PD8B
The position at which the light intensity of the light rays incident on the PD 8A becomes the same as the reference position, the output signal of the PD 8A after photoelectric conversion and the PD
By comparing with the 8B photoelectrically converted output signal,
The reference position can be detected.

Then, the light beam 45 of the light emitted from the light source unit 41 is transmitted through the opening 46 of the mask 44 to the reference position 3.
Is formed into a slender rectangular shape inclined at a predetermined angle with respect to the slit 7, it is possible to accurately detect the reference position without adjusting the position of the light source unit 41, and to reduce the cost of the reference position detection device 40. High accuracy can be achieved.

In the above embodiment, the opening 46 of the mask 44 is formed in a rectangular shape. However, the shape of the opening 46 is not limited to a rectangular shape.
It may be elliptical.

FIG. 8 is a diagram showing a sixth embodiment of the encoder reference position detecting device according to the present invention, and this embodiment corresponds to claim 6. In the present embodiment, a light source section for easily emitting a light beam having an elongated cross-sectional shape is formed, and the same components as those in the first embodiment are denoted by the same reference numerals. , And a detailed description thereof will be omitted.

In FIG. 8, the origin position detecting device 50 of the encoder includes a light source 51, a reference position 3, and a detecting unit 4.
(Not shown).

The light source unit 51 includes an LD (laser diode) 52 as a light source, and a lens 53 for condensing light emitted from the LD 52, and transmits the light beam 54 to the detection unit 4 via the reference position unit 3. Irradiate.

Generally, the LD 52 has a different radiation angle within the beam cross section. Therefore, the beam of the LD 52 is condensed by the lens 53 or is converted into parallel light, so that the cross section 5
4A can form an elongated light beam 54.

Then, the LD 52 or the slit 7 of the reference position portion 3 is formed such that the major axis direction of the cross section 54A of the light beam 54 emitted through the lens 53 is inclined at a predetermined angle with respect to the major axis direction of the slit 7. Arrange them in a crossing state.

The reference position unit 3 and the detection unit 4 are configured in the same manner as in the first embodiment.

Therefore, the origin position detecting device 50 of the encoder according to the present embodiment condenses the light emitted from the LD 52 of the light source 51 by the lens 53 and outputs the light to the reference position 3.
Irradiate the detection unit 4 through the slit 7.

At this time, the light source of the light source section 51 is an LD.
Since the light source 52 is used, the light beam 54 having an elongated cross section can be formed easily and inexpensively, and the reference position detecting device 50 can be made inexpensive.

As described above, the invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to the above, and various modifications can be made without departing from the gist of the invention. It goes without saying that it is possible.

For example, in each of the above-described embodiments, a light source using a semiconductor laser or an LD is used as the light source of the light source unit. However, the light source is not limited to these. For example, FIG. LE as shown in FIG.
D (Light Emitting Diode) 60 may be used. In this case, as shown in FIG. 10, the light emitting surface 61 of the LED 60 can be applied by forming it into an elongated rectangular shape or an elliptical shape. And this rectangular shape,
Alternatively, light emitted from the elliptical light emitting surface 61 is condensed or converted into parallel light by a lens. By doing so, the home position detection device of the encoder can be
The structure can be simple and inexpensive.

In each of the above embodiments, the light forming portion formed at the reference position of the main scale is
Although the case where the slit for shaping the irradiation light and transmitting the light to the detection unit is formed has been described, the light shaping unit formed at the reference position portion of the main scale forms the irradiation light and reflects it to the detection unit. A reflecting member, for example, a reflecting mirror having the same shape as the slit may be used.

[0089]

According to the first aspect of the present invention, a light beam having a cross section perpendicular to the emission direction and having a predetermined elongated cross section is emitted from the light source section to the main scale. A light beam from the light source unit is cut out by a predetermined elongated light shaping unit formed on the scale, and two or more light receiving elements are arranged on the light receiving unit arranged at right angles to the direction of mutual movement with the main scale unit. The light is reflected or transmitted, the light is received by the light receiving means and photoelectrically converted, and the major axis of the cross-sectional shape of the light beam emitted from the light source unit and the major axis of the light shaping unit are inclined at a predetermined angle. Even when a wide slit or a reflecting member is formed as the light shaping part of the light receiving unit, it is changed by the relative movement with the main scale means by two or more light receiving elements of the light receiving means. By detecting the light beam, it is possible to detect the origin position with high resolution.

According to the encoder origin position detecting device of the present invention, the light emitted from the light emitting element is condensed by the cylindrical lens, so that the cross section perpendicular to the light emitting direction has a predetermined elongated cross section. It is possible to emit a luminous flux, and to efficiently and inexpensively emit a linear luminous flux. As a result, it is possible to reduce the cost of the encoder origin position detecting device capable of detecting the origin position with high resolution.

According to a third aspect of the present invention, the light source unit is provided with a mask means having two openings for dividing the light source into two light beams having different phases. Therefore, it is possible to easily form two linear beams, to reduce the noise by using two light beams, and to detect the origin position more simply, inexpensively and with higher resolution. can do.

According to the encoder origin position detecting device of the invention, the light source emits a light beam whose major axis in cross section is substantially perpendicular to the direction of relative movement with the main scale means. Since the light shaping portion is formed with its long axis inclined at a predetermined angle with respect to the long axis direction of the cross-sectional shape of the light beam from the light source portion, the long-axis direction of the cross-sectional shape of the light beam emitted from the light source portion Is disposed at a substantially right angle to the direction of relative movement with the main scale means, without performing fine rotation adjustment of a lens, a light source, and the like, in a state in which the optical shaping unit is inclined at a predetermined angle with respect to the long axis direction. It is easy to assemble, and the origin position can be detected at a high resolution at low cost.

According to the apparatus for detecting the origin of the encoder according to the fifth aspect of the present invention, the light source is formed with an opening having a rectangular or elliptical cross section perpendicular to the emission direction of the transmitted light beam. Since the mask means is provided, a light beam having a cross section perpendicular to the emission direction having a predetermined elongated cross-sectional shape can be inexpensively and efficiently emitted, inexpensively, and with high resolution. The origin position can be detected.

According to the origin position detecting device for an encoder according to the present invention, a laser diode for emitting light beams having different radiation angles within a cross section of the emitted light beam,
And a lens for condensing or collimating the emitted light from the laser diode. Therefore, even with a wide slit, the origin position can be detected at low cost and with high resolution.

According to the apparatus for detecting the origin position of the encoder according to the seventh aspect of the present invention, since the light source is a light emitting diode having a light emitting surface elongated in one direction, it is possible to easily and inexpensively emit an elongated light beam. Thus, even with a wide slit, the origin position can be detected at low cost and with high resolution.

[Brief description of the drawings]

FIG. 1 shows a first example of an origin position detecting device for an encoder according to the present invention.
The perspective view of the principal part of the origin position detection device of the encoder to which the embodiment of the present invention is applied.

2A and 2B show a state of irradiation of a light beam to a detection unit due to a change in a slit position caused by movement of a main scale in FIG. 1;
The figure which shows the change state of (b), (c).

FIG. 3 is a diagram showing a signal intensity of a PD of a detection unit in an irradiation state of each light beam according to a change in a slit position in FIG. 2;

FIG. 4 shows a second example of the home position detecting device for the encoder of the present invention.
The perspective view of the principal part of the origin position detection device of the encoder to which the embodiment of the present invention is applied.

FIG. 5 is a diagram illustrating a third example of the home position detecting device for the encoder according to the present invention;
The perspective view of the principal part of the origin position detection device of the encoder to which the embodiment of the present invention is applied.

FIG. 6 is a diagram illustrating a fourth example of the home position detecting device for the encoder according to the present invention;
The perspective view of the principal part of the origin position detection device of the encoder to which the embodiment of the present invention is applied.

FIG. 7 shows a fifth example of the encoder origin position detecting device of the present invention.
The perspective view of the principal part of the origin position detection device of the encoder to which the embodiment of the present invention is applied.

FIG. 8 shows a sixth embodiment of the encoder origin position detecting device of the present invention.
The perspective view of the principal part of the origin position detection device of the encoder to which the embodiment of the present invention is applied.

FIG. 9 is a front view of a light source using LEDs.

FIG. 10 is a bottom view of the light source of FIG. 9;

[Explanation of symbols]

1, 10, 20, 30, 40, 50 Origin position detection device of encoder 2, 11, 21, 31, 41, 51 Light source 3, 32 Reference position 4 Detector 5, 14 Light 5A, 14A Light cross section 6 Main Scale 7, 33 Slit 33T Long axis direction 8A, 8B PD 13 Cylindrical lens 22, 42 Light emitting element 23, 43 Lens 24, 44 Mask 25A, 25B Opening 26 Ray 26A Cross section 27A, 27B Ray 34 Ray cross section 34T Long axis 45 Light 46 Opening 47 Light 52 LD 53 Lens 54 Light 54 A Light cross section 60 LED 61 Light emitting surface

Claims (7)

[Claims] 1. An encoder origin position detecting device for detecting an origin position of an encoder that outputs an electric signal corresponding to a displacement of a movable body, wherein the device emits a light beam whose cross section perpendicular to the emission direction has a predetermined elongated cross section. A light source section, a main scale means having a light shaping section having a predetermined elongated shape and cutting out the light beam from the light source and reflecting or transmitting the light beam; Light-receiving means for converting, and the light-receiving means comprises at least two or more light-receiving elements arranged in a direction perpendicular to the direction of mutual movement with the main scale means, and Wherein the major axis of the cross-sectional shape and the major axis of the light shaping portion are inclined at a predetermined angle. 2. The light source unit comprises: a light emitting element for emitting light;
A cylindrical lens for condensing the light emitted by the light emitting element,
The origin position detecting device for an encoder according to claim 1, further comprising: 3. A light source unit comprising: a mask unit having two openings for dividing light into two light beams having different phases;
The encoder origin position detecting device according to claim 1 or 2, further comprising: 4. The light source unit emits the light beam whose major axis in a cross-sectional shape of the light beam is substantially perpendicular to the direction of relative movement with respect to the main scale means. 4. The origin of the encoder according to any one of claims 1 to 3, wherein the light source is formed to be inclined at a predetermined angle with respect to a major axis direction of the sectional shape of the light beam from the light source unit. Position detection device. 5. The light source unit according to claim 1, wherein the light source unit includes a mask unit having an opening having a rectangular or elliptical cross section perpendicular to an emission direction of the transmitted light beam. An origin position detecting device for an encoder according to any one of claims 1 to 4. 6. The light source section includes a laser diode that emits light beams having different emission angles within a cross section of the emitted light beam, and a lens that collects or parallelizes the light emitted from the laser diode. The origin position detecting device for an encoder according to any one of claims 1 to 4, wherein: 7. The encoder origin position detecting device according to claim 1, wherein the light source unit includes a light emitting diode having a light emitting surface elongated in one direction as a light source.